This invention relates to a novel plant growth accelerating device, more particularly to a retrofitting aerating root pruner (hereinafter called xe2x80x9cRARPxe2x80x9d) which is adapted to be retrofitted onto the inner face of a conventional plant container which has one or more drain holes at the bottom of the side wall thereof, to form a perforated vertical conduit for aerating planting medium in the plant container in which a plant is grown, to achieve an air root pruning effect and optionally to mechanically prune the roots of a plant which penetrate the RARP, thereby accelerating and enhancing the development and growth rates of the root ball and subsequent vegetative growth of a plant grown in the plant container; to combinations of an RARP of this invention and a root cutting tool (Cutter) adapted to sever roots which have grown into the interior of the RARP; to a kit comprising a plant container with at least one drain hole at the bottom of the side wall thereof and a plurality of the RARPS and optionally also a root cutting tool adapted to sever roots which have grown into the interior of the RARP; and to methods of enhancing the growth rate of plants grown in a plant container on which one or more of the RARP""s which optionally contain such a root cutting tool inserted therein are mounted.
Air root pruning devices and methods are well known in the prior art. See, e.g., U.S. Pat. Nos. 4,442,628; 4,497,132; 4,510,712; 4,574,522; 4,716,680; 4,753,037; 5,222,326; 5,301,465; 5,557,886 and 5,761,848. In each of these devices the air root pruning structure and function is an integral element of the container in which the plant is to be grown, thereby contributing significantly to the cost of its production. U.S. Pat. No. 5,241,784 discloses a slotted air root pruning plant root container that is inserted into a plant container. None of these prior art air root pruning devices has achieved continuing commercial success, for a variety of reasons which include the need for the use of customized containers and one or more of difficulty in removing the mature plant from the plant container; higher production cost of such customized plant containers; loss of planting medium from the plant containers; increased shipping costs because of their lack of stackability; and incompatibility with automatic equipment used by commercial growers for filling plant containers with planting medium.
U.S. Pat. No. 4,175,356 discloses a plant aerator tube with radial apertures in it whose purpose is to reduce the undesirable effects upon the health of the plant of top watering and over watering. Structurally, the aerating tube of the ""356 patent lacks a significant air root pruning effect because only a very limited number of roots of a plant growing in a container in which it is inserted would be affected in an air root pruning way by its presence in the container.
U.S. Pat. No. 4,682,550 discloses an apparatus for loosening, aerating and fertilizing soil plant roots intended for temporary insertion into a predrilled hole in soil for injecting fertilizer, high pressure air and water into the soil. U.S. Pat. No. 3,962,822 discloses a slotted physically or biologically degradable plant container adapted to block growth of roots through the slots thereof when a plurality thereof are positioned side-by-side and to permit growth therethrough when the containers are separately imbedded in the ground.
U.S. Pat. No. 5,615,517 discloses perforated deflector ribs which are bonded to the inner wall of an open ended, water retaining, root barrier envelope which is placed around the root system of a plant to improve delivery of water, aeration and fertilizer to the root system of plants or are integrally formed with the envelope during its construction and impart additional reinforcement to the barrier envelope. The ribs are an integral part of the root barrier envelope and differ structurally in many respects from the aerating root pruning device of this invention.
In our prior issued U.S. Pat. Nos. 5,782,035 and 5,918,415 we disclose an air root pruner adapted to be fitted in an automatic watering garden container.
The RARP of this invention differs inter alia from the air root pruners of the prior art by being dismountably vertically mountable at their top end onto the upper edge of the side wall of a conventional 1, 2, 3, 4, 5 or larger conventional plastic plant container which has at least one drain hole positioned at the bottom of the side wall thereof and at their bottom end through the drain hole and onto the edge of thereof, and, in preferred aspects thereof, by employing the inner face of the side wall of the plant container as an integral element of the air root pruner; and comprising means for limiting the amount of water which can flow directly from the upper surface of planting medium in the plant container through the RARP and out the drain hole. The RARP""s are easily and rapidly mountable on the side wall thereof, they can be used repeatedly because their durable construction and polypropylene or other polymer material renders them virtually indestructible; they are inexpensive to manufacture; and they have a dramatic effect upon the rate of root ball and vegetative growth of a plant grown in a plant container containing one or more thereof mounted on the inner face of the side wall thereof. They differ structurally from the perforated stakes of U.S. Pat. No. 3,962,822, inter alia, by providing a much larger number of apertures in the portion of the wall thereof which faces the plant, thereby achieving an enhanced aeration of the root ball, and additionally they are structured so that mechanical pruning of roots as well as a passive air root pruning effect can be achieved. Because they are mounted on the side wall of a conventional side wall ported round plastic container, they do not require sacrificing sidewall strength and durability of the planting container by requiring aerating apertures in the plant container in order to achieve an aeration effect, a deficiency which has impaired the commercializing of prior art air root pruning planting containers with aeration apertures in their side wall.
The method of this invention provides an economical way of increasing the rate of fine hair and lateral root development and thus the vegetative growth rate of a plant, using inexpensive and reusable devices and plant containers of conventional construction.
It is an object of this invention to provide a RARP adapted to be mounted on the side wall of a side wall drain ported plant container and which lacks most or all of the deficiencies of the above-described prior art aerating and air root pruning devices. It is another object to provide a combination of such a RARP and such a plant container which, when the former is mounted on the inner face of the side wall of the latter, provides a high level of ambient air access to the planting medium along the length of the conduit. A further object is to provide such a combination which promotes uniform distribution of water in the planting medium from its surface to the bottom of the RARP and which has both an air root pruning effect on the roots of a plant grown in planting medium in the plant container. A further object is to provide such a RARP, which comprises means for diverting the tips of the roots of a plant grown in planting medium in the plant container into the interior of the conduit formed by such a combination. Yet another object is to provide such a RARP which is adapted to permit mechanical severing of roots which have penetrated the interior of the conduit formed by the combination of the RARP and the plant container. A still further object is to provide a method of accelerating the rate of growth of a plant which comprises the step of growing the plant in a plant container to which at least one of the RARP""s of this invention is mounted on the inner surface of the side wall thereof. Other objects will be apparent to those skilled in the art to which this invention pertains.
In a generic article of manufacture aspect, this invention relates to a retrofittable aerating root pruner (RARP) which is adapted to be vertically dismountably mounted on the inner surface of a plant container which has at least one drain port at the bottom of the side wall thereof, which is in fluid communication, when mounted on the plant container, with ambient air at its upper end and with a drain port in the plant container at its lower end, which has a plurality of apertures in the face thereof which provide a high ratio of total open area to total wall surface area, and which comprises a first mounting means for detachably attaching the top of the RARP to the top edge of the plant container and a second mounting means for detachably attaching the bottom of the RARP to the edge of the plant container which surrounds the drain port.
In a first embodiment of the first article of manufacture aspect, the RARP is a one-piece elongate rectangular sheet member which is open at both ends and has (a) a plurality of apertures in the face thereof which provide a high ratio of total open area to total wall surface area; (b) which is adapted to be mounted, prior to filling the plant container with plant growing medium, vertically on the interior face of the side wall of the plant container; (c) wings which, when the RARP is mounted on the plant container, snugly contact the inner face of the plant container and maintain the inner face of the RARP in spaced apart relationship therewith so as to form collectively therewith a perforated aerating and drain conduit; (d) whose upper end is adapted to be (i) positioned proximate the top of the plant container, (ii) in communication with ambient atmosphere, and (iii) hooked over the upper edge of the side wall of the plant container by a pair of flexible top catches projecting perpendicularly from a rim which defines the upper end of the RARP; (d) whose lower end is adapted to be (i) positioned proximate a drain port at the bottom of the side wall of the plant container, (ii) in communication with the atmosphere through the drain port and (iii) fitted through the drain port and snapped onto the outer surface of the bottom wall of the plant container by a flexible bottom catch in the form of an extension projecting approximately perpendicularly from the bottom end of the RARP.
In a second article of manufacture aspect, this invention relates to the combination of a one-piece RARP as defined above and a perforated rectangular root cutter plate which is adapted to be slidably and removably inserted into the RARP with one face of the a cutter plate in sliding contact with the interior face of the RARP, whose apertures are positioned so as to be in registry with the apertures of the RARP when the cutter plate is fully inserted in the RARP, whereby aeration of the planting media is facilitated when the cutter plate is in a fully inserted position and roots which have invaded the space between the cutter plate and the inner wall of the plant container can be severed by at least partially withdrawing the cutter plate from the RARP.
In a preferred embodiment of the second article of manufacture aspect, the cutter plate has a canopy on its upper end which covers the aerating space between the inner wall of the cutter and the inner wall of the plant container when the RARP is mounted on the plant container with the cutter plate inserted in RARP, thereby preventing planting media and the trash from falling into the aerating conduit.
In a third article of manufacture aspect, this invention relates to the combination of a RARP as defined above, alone or in combination with a root cutter plate as defined above, and a conventional injection molded plastic plant container with at least one drain port at the bottom of the side wall thereof, onto which the RARP is mounted or is adapted to be mounted.
In an alternative embodiment of the first article of manufacture aspect of this invention, the RARP is a 3-piece embodiment which comprises (a) a pair of elongate semi-cylindrical members which are joined by a living hinge and comprise means to lock them together in a closed position to form a cylindrical conduit which is adapted to extend from the bottom of the side-wall ported plant container to the top thereof, and (b) an elongate strap member with a catch member on one end adapted, which strap member is adapted to be mounted vertically along the wall of the conduit with the end thereof bearing the catch member unattached and projecting away from the lower end of the side wall of the conduit and the catch member is adapted to be inserted through the drain hole of the plant container and is dismountably fitted onto the upper edge thereof, which conduit comprises (i) a plurality of apertures therein which impart a high ratio of open area to solid surface area to the side wall of the conduit; and (ii) latch means on its upper end for dismountably mounting its upper end over and onto the upper edge of the side wall of the plant container.
In a first method of use aspect, this invention relates to a method of using a RARP of this invention to promote the growth rate of a plant by air root pruning the roots thereof, which comprises the steps of mounting a RARP as defined broadly hereinabove onto the interior face of the side wall of a ported plant container as defined herein, before the plant container is filled with planting medium, thereby forming an aeration and drain conduit extending from above the surface of the planting medium to the bottom of the plant container; filling the plant container with planting medium; and thereafter planting a plant in the planting medium before the root ball of the plant has fully formed, so that the tips of the growing roots of the plant contact the RARP as the root ball increases in size; and optionally thereafter severing the roots of the growing plant which have invaded the interior of the conduit formed by the aerating root pruner device.
In a preferred method of use aspect, the first method of use comprises the optional additional step of thereafter severing roots of the growing plant which have invaded the interior of the aeration and drain conduit formed by mounting the RARP on the interior face of the side wall of the plant container by at least once during the period while the plant is growing in the plant container fully inserting into the interior of the conduit a handled cutter tool which is slideably and removably insertable therein; and thereafter withdrawing the cutter tool from the conduit.